Update contact

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full behavioral burden. It does disclose one genuinely non-obvious trait (PATCH-style merge rather than full replacement), but says nothing about permissions, failure when contactId is unknown, side effects of changing email, or idempotency.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, zero filler, with the resource and the partial-update rule front-loaded. Nothing could be cut without losing meaning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a mutation tool with no annotations, no output schema, and six undocumented parameters, the description is too thin. An agent gets the merge behavior but lacks field-level semantics, error conditions, and any hint about permissions or the shape of the result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% across 6 parameters, so the description must compensate and does not. It never enumerates the updatable fields (name, email, phone, title, companyId) or clarifies the required contactId, referring only to generic 'fields'.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Update fields on an existing contact') and adds the partial-update qualifier, so an agent can distinguish it from create_contact or get_contact. It never names a sibling explicitly, but the resource is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description conveys the partial-update contract ('only provided fields are changed'), which is useful for invoking it, but it gives no guidance on when to use update_contact versus create_contact, no prerequisites, and no note that contactId must reference an existing contact.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.